1. Field of the Invention
The invention relates to a method of and apparatus for restoring unknown samples of an equidistantly sampled signal, which samples are considered to be invalid, on the basis of replacement values derived from an environment of samples which are considered to be valid and occur previous to and subsequent to an interval containing the samples to be restored.
2. Description of the Related Art
Such a method and arrangement are disclosed in Netherlands patent application 8,304,241, which corresponds to pending U.S. application Ser. No. 07/442,495, filed Nov. 27, 1989, now U.S. Pat. No. 5,025,404, assigned to the present assignee, of which applicant herein is a named co-inventor.
According to these prior art arrangements, which employ higher order autoregressive procedure, the value of a sample to be restored is estimated from a linear combination of a number of known samples described by this order. The order of the recursion procedure is determined in dependence on the number of samples to be restored. This means that a number of prediction coefficients depending on the type of signal to be restored must be calculated before a most appropriate recursion formula can be drawn up for each samples. From the recursion equations thus determined, a system of equations is formed in which the estimated values (estimators) of the samples to be restored are present as unknown factors.
Although the prior art arrangements are suitable for recovering audio signals, such as music or speech, the bulk and complexity of the computational operations to be performed are such that it becomes problematical to satisfy with an economically justifiable structure the requirements imposed on performance properties of specific systems. More specifically, these prior art techniques are less suitable for recovering signals in which comparatively long intervals, having an order of magnitude of, for example, 10 msec, and containing samples which must be considered as invalid, occur.